Question

If we are given start row, start column, endrow, endcolumn. How to print a diagonal line in an array using ONLY while loop in C?  Print a 4 in the diagonal position.

Answer 1

#include<stdio.h>

void space(int n)
{
    for(int i=0;i<n;i++)printf(" ");
}

void southeast(int m[][3],int s_row,int s_col,int e_row,int e_col)
{
    int temp_col=s_col;
    int temp_row=s_row;
    while(temp_row<=e_row)
    {
        space(temp_row-s_row);
        printf("%d\n",m[temp_row][temp_col]);
        temp_row++;
        temp_col++;
    }
}

void northwest(int m[][3],int s_row,int s_col,int e_row,int e_col)
{
    int temp_col=e_col;
    int temp_row=e_row;
    while(temp_row<=s_row)
    {
        space(temp_row-e_row);
        printf("%d\n",m[temp_row][temp_col]);
        temp_row++;
        temp_col++;
    }
}

void northeast(int m[][3],int s_row,int s_col,int e_row,int e_col)
{
    int temp_col=e_col;
    int temp_row=e_row;
    while(temp_row<=s_row)
    {
        space(s_row-temp_row);
        printf("%d\n",m[temp_row][temp_col]);
        temp_row++;
        temp_col--;
    }
}

void southwest(int m[][3],int s_row,int s_col,int e_row,int e_col)
{
    int temp_col=s_col;
    int temp_row=s_row;
    while(temp_row<=e_row)
    {
        space(e_row-temp_row);
        printf("%d\n",m[temp_row][temp_col]);
        temp_row++;
        temp_col--;
    }
}

int main()
{
    int m[][3]={{1,2,3},{4,5,6},{7,8,9}};
    int s_row=2,s_col=0;
    int e_row=0,e_col=2;
    if(s_row<e_row && s_col<e_col)southeast(m,s_row,s_col,e_row,e_col);
    else if(s_row>e_row && s_col>e_col)northwest(m,s_row,s_col,e_row,e_col);
    else if(s_row>e_row && s_col<e_col)northeast(m,s_row,s_col,e_row,e_col);
    else 
        southwest(m,s_row,s_col,e_row,e_col);

    return 0;
}

Output

One thing I could not understand what does "Print a 4 in the diagonal position." mean? Tell me in the comment.